Tag: electronics

This is the final post about the rover, I promise. In addition to the changes made to the electronics box, we also needed to get data from the wheels. Each wheel is a self contained unit with a battery, motor, and speed controller, which is sent pwm signals from the mbed. We needed to get the power draw from each wheel and this is the board I designed to do it.

In another episode of clearing up old projects, here’s a controller I made for the rover that acts as an emergency override and also allows somebody nearby to drive it around. The rover is typically controlled over the internet but there are times you may want to be able to control it without the internet, including when the internet connection is down. Any signal from the controller also overrides the signal from the internet user so it can be used as an E-stop.

Last summer I started working with the rover team to modify the rover to be used for another research project. The original rover did extremely well at the competition but they were working under tight time restrictions and almost all of the work was done by undergrads. That meant there was a lot of work needed to fix and modify it.

Here’s my schematic and board design for a simple low side switch using a N channel mosfet. It’s a simple circuit that has a input for positive and negative and an output for positive and negative connections. Pretty self explanatory. It seems like every time I go to work with mosfets I have to spend a good 5-10 minutes reminding myself how they work. So here’s a reminder to myself for the next time I go looking and maybe it’ll help somebody else out.

Here’s my schematic and board design for a simple high side switch using a P channel mosfet. It’s a simple circuit that has a input for positive and negative and an output for positive and negative connections. Pretty self explanatory. It seems like every time I go to work with mosfets I have to spend a good 5-10 minutes reminding myself how they work. So here’s a reminder to myself for the next time I go looking.

One of the projects I’m working on is a robot that has reflectance sensors around its circumference. I had trouble finding sensors that would work in the 0.25-0.75 inch range but eventually found the RPR-220. To mount this sensor, I made a breakout board with space for resisters and connections for positive, negative, and signal. Continue reading “Using the RPR-220 and a Breakout Board”→

I’ve been using I2C a lot lately and something that keeps popping up is the need to send large numbers. I2C normally only sends a single byte at a time so you are limited to 255 as the largest number. This post will show you how I break large numbers apart to send them over I2C and reassemble them on the other side.